Preheat oven to 450°. Grease 15 muffin cups. Combine water and shortening in large saucepan. Bring to a rapid boil. Remove from stove. Add flours and salt all at once. Stir until mixture forms a ball that leaves the sides of pan. Cool slightly. Add unbeaten eggs, one at a time, beating well with electric mixer after each egg is added. Drop by tablespoons into prepared cups to form a goose egg-sized mound. Bake 20 minutes. Then reduce heat and bake at 350° for 20 minutes. Makes 15 popovers.